OpenSSH 7.0 disables several pieces of weak, legacy, and/or unsafe
cryptography.
* Support for the legacy SSH version 1 protocol is disabled by default at
compile time. Note that this also means that the Cipher keyword in
ssh_config(5) is effectively no longer usable; use Ciphers instead for
protocol 2. The openssh-client-ssh1 package includes „ssh1“, „scp1“,
and „ssh-keygen1“ binaries which you can use if you have no alternative
way to connect to an outdated SSH1-only server; please contact the
server administrator or system vendor in such cases and ask them to
upgrade.
* Support for the 1024-bit diffie-hellman-group1-sha1 key exchange is
disabled by default at run-time. It may be re-enabled using the
instructions at http://www.openssh.com/legacy.html
* Support for ssh-dss, ssh-dss-cert-* host and user keys is disabled by
default at run-time. These may be re-enabled using the instructions athttp://www.openssh.com/legacy.html
* Support for the legacy v00 cert format has been removed.​